Radial flow rotary vaned machines are well known in the art. These machines can be constructed much more compactly and simply than can their axial flow counterparts.
Traditionally, centrifugal compressors and centripetal turbines have utilized a single rotor construction wherein the blades carried by the rotor are rotated at a uniform angular velocity. Centrifugal forces on the blade portions disposed furthest from the rotational axis tend to elongate the blades, and at high speeds could precipitate blade failure. To obviate this problem, the rotor is often operated at lower speeds to reduce loading on the most heavily stressed blades. As a result, those stages closest to the center of the rotor contribute relatively little to the treatment of the gas contained by the machine.
Exemplary of the state of the art is the forward compressor section of the turbine engine shown in the U.S. Pat. No. 4,030,288 issued to Davis et al. The compressor section comprises two longitudinally displaced bladed rotor sections, which operate at the same tip speeds, and a diffusion chamber intermediate the rotor sections. The radial extension of the blades, from the rotational axis of a shaft, increases progressively at each section toward the air outlet end. At high speeds the blade portions which are disposed furthest from the rotational axis experience the greatest tip speeds, and are severely stressed.
The present invention is directed to overcoming one or more of the problems as set forth above.